Blocking oscillator



y 29, 1952 G. D. PERKINS 2,605,407

' I BLOCKING OSCILLATOR Filed Jan. 5, 1946 INPUT OUTPUT INVENTOR GEORGE D. PERK IN S ATTORNEY l atented july 29, 11952 G a -s 1 1-, lli k nf i- 4 a sisg mesne" assignments; to theTUmt quency resonant tank circuit and utilizing cath= odeibias;

Heretofore', blocking oscillators werelim'ited'in applicationbecause the dead time during which the oscillator remained inoperative, was relativelyjlong'. Furthermore, conventional type: blocking "oscillators generally required iron core" transiormers and external 'bias supplies.

'A' pri ary object of the present invention is to generallvim'prove blockingjogscillatorsby elimi ating, fth'e"fofregoing difiiculti'es.

' Anothef'object of the present invention is'to provide a blocking oscillator that can either be triggered or free running. and utilizes a'high frequency resonant circuit'therein.

A further object-is-to provide a blocking oscillator which requires no external source of power fo'r'biasing. I

These and other objects will-be apparent from the following speclfication'when "taken with the accompanying drawing which is a circuit diagram of-an embodiment of the invention.

Referring! to the drawing'there is illustrated an electron tube (triode) blocking oscillator-i4; A cathodebiasing resistor l9 shunted by capacitor'20 is connected to the cathode I2 of electron tube M. The latter are of such values asto place when in operation, a rather high bias on the cathode and thereby normally prevent constant oscillation of the electron tube. An LCR network (tank circuit), composed of resistor IT, inductor i8, capacitor I 5 and inductor I6 is connected in the circuit with the grid I I of the electron tube I 4. Anode I3 of the electron tube I4. is connected to a positive power supply 22 through an inductor 2! which is inductively coupled to the inductor IS in such a manner as to tend to make the electron tube Constant oscillation as previously mentioned is prevented by the rather high cathode bias. Capacitor 24 is a radio frequency return from the anode to the cathode.

When a positive input trigger is applied through coupling capacitor 2'3 to the grid LCR network at the junction of resistor I1 and in ductor [8, this trigger overcomes the bias on the tube 14 and the circuit oscillates strongly, thereby causing the current through the cathode resistor I9 to increase rapidly and again raise the bias to the point where oscillations can no longer be sustained. The cathode voltage rise during this time is extremely sharp, thereby producing the M oscillate.

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scams; (or. ssh-27 cillationceases, and"th'e"c ircuit quickly return fre uencies; Thus the dead timepfithi trip tojsecure'by Letters Bate nt'and cl made, free runninglor' t i re 1 States--of--- j v j output: pulse; 'rne charge'fstoredjon the r:"t "d capae'itorfzo discharges" exponentially'whe us to a quiescent statere'ady for"'tl ie'nextI- ri r ris me o e; ta mi dependentontheoscillationfrequency; hi ch turn is determin'ed'by the circuit constant-s period or; one cycle," at theifrequencyj of oscil no offthej gridtank; circuit. is: ete -a siderably sh-orterfthan th'e per j output W156. As jjthej oscillation frequ cy creased the rise jtim decreases, and 1 valuefof cathfode capaicitorj2i!- is'd a tank circuit frequency'of about 200 no cathode capacitor. i-sfrequired. d cay timedecreases with an'in" qluenjcy, and becomes. very short for the? ing blcckingf oscillator"will beveryfshior. w f rfquencies are empl pydf. is. fnrth n m thed'raw'ing, there is noneed core transformer ran external adjustment of the bias, the oscillator The inventiondescribjed in'thej foregoing fication'need'notjbe limitedgtofthe det' w which are considered to. be illustrjat eiqf on form theinvention"maytakeg- What v 1.1 A; blocking oscillator, for, p g put pulsewhen'f triggered byjan .mp t: trigge 1 comprising," an electron tube having an" anodej"a' cathode and a control grid, a resonant tank circuit connected between saidgricl and a point of reference potential, said resonant tank circuit having a period short compared to the duration of said output pulse, an inductor inductively coupled to said tank circuit, said inductor being connected between said anode and a source of positive potential, resistive means connecting said cathode to a said point of fixed reference potential, said resistive means having an impedance such that said electron tube is normally biased to a non-oscillatory state, coupling means as sociated with said tank circuit providing means for introducing said trigger to said tank circuit and means for deriving an output signal from across said resistive means.

2. A blocking oscillator for providing an output pulse when triggered by an input trigger comprising an electron tube having an anode, a cathode and a grid, a resonant tank circuit connecting said grid to a point of reference potential, an inductor coupling said anode to a point of positive potential, said inductor being regeneratively coupled to said tank circuit, a resistor connectin said cathode to said point of reference potential, said resistor having a value such that said circuit is normally biased to a non-oscillatory state, coupling means associated with said tank circuit providing means for introducing said trigger to said tan kvcircuit, whereby, said-,circuit, upon, introduetion of a trigger causes the anOde currentin said electron tube to increase until limited by the voltage drop across said resistor, and means,- for obtaining an output signal from across said resistor. 3. A blocking oscillator for providing an pulse when triggered by an input trigger comprising an electron tube having an anode, apathode and a control grid, a resonant tank circuit connecting said grid'to a point of reference pooutput H 4 said point of reference potential said bias means comprising of a capacitor in shunt with a resistor, said bias means having an impedance such that said electron tube is biased to a non-oscillatory state by the first pulse of anode current through said tube, whereby said circuit upon initiationof oscillation in said tank circuit causes the anode current .to increase sharply until limited by the increase in potential across said bias means, and means for coupling an output signal from said cathode.

'6. A blocking oscillator for providing an output pulse comprising an electron tube having an janode, a cathode and a control grid, 9, parallel tential, the period of the resonant frequency of said tank circuit being short compared to the time duration of said output pulse, an inductor connected between. said anode and point of positive potential, said inductor being regeneratively coupled'to ,said'tank circuit, a resistive means connecting said cathode to said point of reference; potential said resistivefrjneans having an imped-' tive potential to said point of reference potential.

5. 'Ablocking oscillator for providing an' output pulse fcomprisingjan electron tube having an anode, a cathode and a control grid, a resonant;

tank circuit connecting said grid to a point'of reference potential, the-period of the resonant frequency of said tank circuit being short compared' to the timeiduration of, said output pulse, an inductor connected between said anode and a point of positive'pote'ntial, said inductor being regeneratively coupled,to'said tank circuit, high frequency by-passm'eans connecting said point of positive potential to said point of reference, potential; bias means connecting said cathodeto resistor-capacitor combination connected at one terminal thereof to said cathode, a second terminal of said combination serving as a point of *reference, said resistor-capacitor combination having an impedance such that said electron tube is normally biased to anon-oscillatory state, a f rst inductor having one terminal thereof coupled to said grid and a second terminal thereof connected to said point of reference through a second resistance, a second inductor having a first terminal thereof coupled to said grid through a second capacitor and a second terminal thereof connected to said point of reference, said first andfsecond inductors, said second resistor and said second capacitor forming a tuned circuit having a period short compared to the duration of the output pulse from said oscillator, a third inductor coupled between said anode and a sourceo-f positive potential, said third inductor being inductively coupled to said second inductor, and means for coupling an input signal across said second resistor thereby to initiate anode current flow in said electron tube. 1

GEORGE D. PERKINS.

REFERENCES CITED The following references are of record in the file of this patent:

Y UNITED STATES PATENTS Number Name Date 2,212,202 Faudell et a1; Aug. 20, 1940 2,254,087 Percival Aug. 26, 1941 2,257,663 Albrecht Sept. 30, 1941 2,266,668 Tubbs Dec. 16 1941, 2,297,742 Campbell Oct. 6, 1942 2,355,606 Shannon Aug. 16, 1944 "Applegarth Jan. 3, 1950 

